WO2016045998A1

WO2016045998A1 - Circuit device and method for ascertaining a state of a locking conductor loop

Info

Publication number: WO2016045998A1
Application number: PCT/EP2015/070922
Authority: WO
Inventors: Pulcherie Ide Fouedjio; Karl-Heinz Winkler
Original assignee: Conti Temic Microelectronic Gmbh
Priority date: 2014-09-24
Filing date: 2015-09-14
Publication date: 2016-03-31
Also published as: DE102014219235A1; US10139443B2; DE102014219235B4; CN107003111A; EP3197704B1; US20170307674A1; EP3197704A1; CN107003111B

Abstract

The invention relates to a circuit device (SV) for ascertaining a state of an electric locking conductor loop (VS) for monitoring a high-voltage component (HK), comprising: - a current connection (SA1) for electrically connecting to a voltage source; - a ground connection (ML) for electrically connecting to an electric ground (MS); - a positive connection (PA) for electrically connecting to a line end (LE1) of the locking conductor loop (VS); - a negative connection (NA) for electrically connecting to another line end (LE2) of the locking conductor loop (VS); - a measuring arrangement (MA) for measuring the voltage potential (Φ) at the negative connection (NA) when two different currents (I1, I2) are flowing from the current connection (SA1) to the ground connection (ML) via the negative connection (NA); and - a detection arrangement (EA) which comprises a comparison unit (KP) for comparing each of the two voltage potential (Φ) measurement values (Φ1, Φ2) measured for the two currents (I1, I2) with two specified potential reference values (Ur1, Ur2 or Ur3, Ur4) and which is designed to detect whether the negative connection (NA) is electrically short-circuited with the positive connection (PA), the current connection (SA1), the ground connection (ML), or none of these connections (PA, SA1, ML) on the basis of the comparison results of the comparison unit (KP).

Description

description

Circuit device and method for determining a state of a locking conductor loop

The present invention relates to a circuit device for determining a state of a locking conductor loop, wherein the locking conductor loop is in turn adapted to monitor a high-voltage component. Furthermore, the invention relates to a contact protection circuit with a said circuit device and a said interlock conductor loop, as well as a vehicle with said contact protection circuit. In addition, the invention relates to a method for determining the state of said locking conductor loop.

Modern vehicles, in particular hybrid electric or electric vehicles, include high-voltage vehicle power supply systems or high-voltage components, such. As traction batteries, electrical machines, power electronics and / or supercapacitors whose operating voltages are well over 60 volts and even over 450 volts. Voltages of over 60 volts are life-threatening for humans and animals. Therefore, the high-voltage components are equipped with various contact protection elements, the activation of which signals possible dangers to people and animals emanating from the high-voltage components. The contact protection elements are constructed for example as Verrie ^¬ gelungselemente at the plug contacts or connections of the high-voltage components or their housings. If the plug contacts or plug-in connections of the high-voltage components are disconnected or the housings of the high-voltage components are opened, the contact protection elements are activated.

In addition, the modern vehicles are equipped with touch protection circuits, the electrical Verriegelungslei ^¬ ter loops (in English "interlock loop" or "Interlock Loop Circuit") include. With the interlocking conductor loops the contact protection circuits monitor the contact protection elements. If the contact protection elements activated in the aforementioned manner, the Verriege ^¬ ment conductor loops are electrically interrupted. If such interruptions of the locking conductor loops are detected by the corresponding contact protection circuits, then they send, for example, corresponding control signals to the affected high-voltage components and deactivate them. The deactivation of the high-voltage components occurs, for example, by electrically disconnecting the high-voltage components from the high-voltage on-board electrical system branch or from the vehicle electrical system, by switching off or by discharging the high-voltage components, such as the supercapacitors.

If errors occur in the contact protection circuits insbesondre in the locking conductive loops, one, it may happen that the high-voltage components are incorrectly disabled in non-hazardous situations or be reversed unreliable disabled ge ^¬ potentially fatal situations and thus be a source of danger for people and animals.

Thus, the object of the present invention is to allow reliable protection of humans and animals from the dangers of the high-voltage components, esp. Of a vehicle.

This object is solved by subject matters of the independent claims. Advantageous embodiments are the subject of Un ^¬ teransprüche. According to a first aspect of the invention, a scarf ^¬ tion device for determining a state of an electrical interlock conductor loop, esp. A contact protection circuit of a vehicle, especially a hybrid electric / electric vehicle, provided, the Verriege- ment ladder loop in turn for monitoring at least one high-voltage component esp. Of the vehicle, especially the hybrid electric / electric vehicle, is set up. The circuit device comprises a power connection, via which the circuit device electrically ver ^¬ is connected to a voltage source or a positive power terminal of the voltage source.

Furthermore, the circuit device comprises a ground connection, via which the circuit device is electrically connected to electrical ground. In addition, the circuit device includes a positive terminal and a negative terminal. Via the positive terminal, the circuit device is electrically connected to one line end of the interlock conductor loop and via the negative terminal to another line end of the interlock conductor loop.

The circuit device further comprises a measuring arrangement which is set up at the negative terminal a first

To measure voltage potential (that is, as a first potential reading) when a first current (including a current with a current of 0 amperes) flows from the power connector via the negative terminal to the ground terminal. The measurement ^¬ arrangement is further adapted, to the negative terminal of a second voltage potential (ie measured value as a second potential) attribute, when a second, from the first current (by, for example, a different current value or an opposite current flow direction) (alternate current including a current with a current of 0 amperes) flows from the power connection via the negative terminal to the ground terminal. For this purpose, the measuring arrangement has a signal input, via which the measuring arrangement is electrically connected to the negative terminal and measures the voltage potential at the negative terminal.

The circuit device also includes a determination arrangement which is electrically connected on the signal input side of the signal arrangement of the measurement arrangement. The determination arrangement comprises a comparison unit that is set up to carry out the first potential transfer of the measurement arrangement. Compare almesswert with a first and a second Potentialrefe ^¬ threshold value and to compare the second, passed from the measuring arrangement potential measurement value with a third and a fourth potential reference value. The determination arrangement is also set up based on the

Comparative unit comparison results to determine whether the negative terminal is electrically shorted to the positive terminal, the power terminal or the ground terminal, or to any of the three terminals (that is, the positive terminal, the power terminal, or the ground terminal).

The circuit device may preferably be formed on a circuit carrier, wherein the detection arrangement may, for example, be designed as a microprocessor. Alternatively, the circuit device can be designed distributed on a plurality of circuit carriers.

The invention is based on the recognition that there are various possible sources of error, which convert the interlocking conductor loop into the various faulty states. Among the possible fault conditions, the following three error conditions are particularly relevant to the functionality of the locking conductor loop or particularly dangerous for people and animals and must therefore be a ^¬ clearly separated from the rest of faulty states of locking conductor loop and treated separately. These states are:

an electrical interruption in the Verriegelungslei ^¬ terschleife;

an electrical short circuit of the interlock conductor loop with the voltage source;

an electrical short circuit of the interlock conductor loop with the electrical ground.

Based on this knowledge, a solution has been sought in the context of this invention with which these three error states can be determined unambiguously and reliably from one another and from the remaining erroneous states. The solution thus provided was a circuit arrangement with a measuring arrangement with which a voltage potential can be measured at a line end of the interlock conductor loop which is electrically connected to a negative terminal of the circuit device. The voltage potential at this end of the line represents a voltage drop between said output end of Verriegelungslei ^¬ terschleife and electrical ground. In the process, this voltage changes as a function of the state of the interlocking conductor loop, in particular the three aforementioned relevant fault states of the interlocking conductor loop.

In the context of the invention, however, it has been found that the aforementioned residual faulty states in the interlocking conductor loop also lead to changes in the abovementioned

Lead voltage. In addition, it has been found that even in the circuit device itself errors can occur, leading to changes in the voltage mentioned. In order to be able to unambiguously and reliably separate the three relevant fault states from each other and from the remaining faulty states in the interlocking conductor loop and the faults in the circuit device, it has been provided within the scope of the invention to carry out at least two measurements of said voltage at different electrical currents, wherein these Distinguish currents from each other by their currents or current flow directions. As a result of the multiple measurements (at least two measurements), at least two potential measured values of the mentioned voltage or of the corresponding voltage potential are obtained, which are then compared by at least two potential reference values determined beforehand by a downstream determination arrangement. The comparison results are then logically linked to one another by the Determined ^¬ lung arrangement and compared with previously determined logic (reference) threads, the three error conditions, an error-free state of the locking loop conductor to the respective above-described each and the non-relevant residual error states are assigned.

Based on the comparison result of the logic operations, the current state of the interlock conductor loop, in particular with regard to the three relevant error states, can then be determined unambiguously and reliably.

Thus a possibility is provided, with which the high-voltage components, esp. A traction battery, a Leis ^¬ consumer electronics, an electrical machine, a supercapacitors sator (so-called "super-cap") of a vehicle, especially a hybrid electric or electric vehicle, can be safely monitored and thus the people and animals can be reliably protected from the dangers of the high-voltage components.

Preferably, the circuit device further comprises a controllable, in particular controllably switched on / off, current source connected between the negative terminal and the ground terminal and arranged to provide the two aforementioned currents (including the currents of currents of 0 ampere).

The current source is preferably as a constant current source or as a scalable or modulatable

Power source formed.

The current source preferably comprises a current mirror ^circuit which is set up to provide load-independent currents which remain constant independently of the voltage fluctuations in the operating voltage of the voltage source.

The switching device preferably comprises a Strombe ^¬ grenzungsschaltung which is electrically connected between the power terminal and the positive terminal, and between the power terminal and the negative terminal and the measuring arrangement. The current limiting circuit is used to limit by the locking conductor loop or the Circuit device flowing currents and thus to protect the circuit device from an overvoltage or a

Overcurrent. Preferably, the circuit device further comprises a bypass resistor electrically connected between the power terminal and the negative terminal and between the positive and negative terminals, respectively. The bridging resistor serves to bypass the interlock conductor loop when it is broken, and thus the electrical connection between the positive and negative terminals.

The measuring arrangement preferably comprises a protective circuit ^¬ processing unit which is connected between the signal output of the measuring arrangement and the signal input of the decision means and is arranged to protect the determining arrangement before over- and / or under-voltage.

According to a further aspect of the invention, a contact protection circuit is provided for monitoring at least one high-voltage component, in particular of a vehicle, especially a hybrid electric or electric vehicle. The shock protection circuit for an electrical ^¬ summarizes Verrie ^¬ gelungsleiterschleife for monitoring the at least one high voltage component and a previously described circuit ^¬ device for determining the state of the locking ^¬ conductor loop. In this case, the circuit device is electrically connected via the positive connection with an electrical line end of the locking conductor loop and via the negative connection with a further electrical line end of the locking ^¬ conductor loop.

According to still another aspect of the invention is a vehicle, esp., A hybrid electric or electric vehicle, provided that at least one high-voltage component, esp. A traction ^¬ battery, power electronics, an electric machine and / or a super capacitor, and at least one previously described contact protection circuit for monitoring the at least one high-voltage component.

According to still another aspect of the invention provided a method for determining a state of an electric conductor loop lock previously described above with a ^¬ be signed circuit device.

According to the method, a first current (including a current of zero amperes) is generated flowing from the power terminal of the circuit device via the negative terminal to the ground terminal of the circuit device. While the first current flows (or no current flows), the voltage potential is measured as a first potential measurement value at the negative terminal of the circuit device. The first potential measurement value is then compared to a first potential reference value and a second potential reference value, wherein the second Potentialrefe ^¬ Limit value is greater than the first potential reference value.

It is further a second, from the first current (by, for example, a different current or a reverse current flow ^¬ direction) deviating stream (including a current with a current of 0 ampere) are generated, also of the power terminal of the circuit device on the negative terminal flows to the ground terminal of the circuit device. While the second current flows (or no current flows), the voltage potential is measured as a second potential reading at the negative terminal of the circuit device. The second potential measurement value is at ^¬ closing compared with a third reference value potential and a fourth potential reference value, said fourth potential greater than the third reference value is Potentialrefe ^¬ Limit value.

A faultless closed and thus electrically conductive state of the interlock conductor loop is detected if the first potential measurement value between the first and the second Potential reference value is located and at the same time the second Potenti ^¬ almesswert is greater than the fourth potential reference value.

If the two above-mentioned logical connections between the two measured potential measured values and the four potential reference values are not present at the same time, a faulty state of the interlocking conductor loop is assumed. Preferably, an electrical interruption of the Verrie ^¬ gelungsleiterschleife is detected if the first potential ^¬ reading is smaller than the first potential reference value and at the same time the second potential value is greater than the fourth potential reference value.

Furthermore, an electrical short circuit of the interlock conductor loop or of the negative terminal of the circuit device to the power connection of the circuit ^¬ device or to the positive power connection of the voltage source is preferably detected, if the first potential reading is greater than the second potential reference value and at the same time the second potential value greater as the fourth potential reference value. Analog is preferably an electrical short circuit of

Interlocking conductor loop detected to the ground terminal or to the electrical ground, if the first potential value is less than the first potential reference value and at the same time the second potential value is less than the third potential reference value.

If none of the above-mentioned logic operations is present, a further, not clearly assignable, faulty state of the interlock conductor loop or the circuit device is assumed.

Advantageous embodiments of the circuit device described above are, as far as the above-mentioned Touch circuit or transferable to the above-mentioned vehicle or to the above method, also to be regarded as advantageous embodiments of the contact protection circuit, the vehicle or the method.

Analogous advantageous embodiments of the method described above, as far as the above-described

Circuit device, on the above-mentioned touch circuit or transferable to the above-mentioned vehicle, also to be regarded as advantageous embodiments of the circuit device, the contact protection circuit and the vehicle.

In the following, exemplary embodiments of the invention will be explained in more detail with reference to the accompanying drawings. Showing:

Figure 1 in a schematic circuit topology a

Touch protection circuit with a circuit device according to an embodiment of the invention;

2 shows in a flowchart a method for determining a state of an electrical locking ^¬ conductor loop with the circuit device according to another embodiment of the invention.

FIG. 1 shows a contact protection circuit BS of an electric vehicle, not shown in the figure, for one or more high-voltage components HK of the electric vehicle, which comprise, for example, a traction battery, an electrical machine, a super-capacitor and power electronics circuits.

Operating voltages of these high-voltage components HK are well above 60 volts and thus lebensge ^¬ fährlich for humans and animals. To protect humans and animals against life-threatening electric shocks, the high-voltage components HK are electrically insulated from the environment by appropriate housings or other insulation measures. Are one or more housings or one or more insulation measures of the high-voltage components HK For example, by an external mechanical action be ^¬ injured or unintentionally opened or deactivated, so threatened for people and animals a mortal danger from electric shock.

In order to counteract this, the contact protection circuit BS comprises a locking conductor loop VS for monitoring the high-voltage components HK or their housings or their other insulation measures.

The locking conductor loop VS is formed as an electrical line with a first line end LEI and a second line end LE2 and comprises one or more controllable switches ST, which depend on the states of the high-voltage components HK and their housing or other insulation measures in a subsequently described Way closed or opened. If all switches are closed ST error-free, the locking loop conductor VS is "closed", wherein the two line end LEI, LE2 are electrically shorted together. However, if at least one switch ST is opened, the locking ^¬ conductor loop VS is interrupted and the two line end LEI, LE2 are electrically separated from each other. The contact protection circuit BS further comprises a circuit device SV with which the contact protection circuit BS detects the state of the interlock conductor VS and recognizes potential dangers depending on the state of the interlock conductor VS.

The circuit device SV has a positive terminal PA and a negative terminal NA. Via the positive terminal PA, the circuit device SV is electrically connected to the first line end LEI of the interlock conductor loop VS. Via the negative terminal NA, the circuit device SV is electrically connected to the second line end LE2 of the interlock conductor loop VS. The circuit device SV further comprises a first

Power connection SA1 via which the circuit device SV is electrically connected to an external, not shown in the figure DC voltage source of a low-voltage electrical system branch of the electric vehicle. The DC voltage ^¬ source provides the circuit device SV an operating voltage Vss, which is well below 60 volts.

The circuit device SV also has a second power connection SA2 and a third power connection SA3, the operation of which will be described below.

The circuit device SV also has a ground connection ML via which the circuit device SV is electrically connected to the electrical ground MS (body of the electric vehicle).

The circuit device SV further comprises a current limiting circuit SB which is electrically connected between the first power terminal SA1 and the positive terminal PA and between the first power terminal SA1 and the negative terminal NA, respectively. In this case, the current limiting circuit SB is in the form of a star connection with a star point ST and comprises a first current path SD1 between the first power connection SA1 and the star point ST, a second current path SD2 between the positive connection PA and the star point ST and a third current path SD3 between the star point ST and the negative terminal NA. In the first current path SD1, the current limiting circuit SB has a first resistor RH. In the second current path SD2, the current limiting circuit comprises a second and a third resistor R12, R13 to SB, which are ge ^¬ connected in parallel to each other. In the third current path SD3, the current limiting circuit SB has a bridging resistor Rb. The bypass resistor Rb may also be arranged in the first current path SD1. Similarly, the current limiting circuit SB may include more or fewer resistors depending on the embodiments. The circuit device SV also comprises a current source SQ, which is electrically connected between the negative terminal NA and the ground terminal ML or between the bridging resistor Rb and the ground terminal ML. The current source SQ is designed as a controlled switchable current source and can currents of at least two different current values, such. B. 0 or 10 milliamps generate. For this purpose, the current source SQ comprises a current mirror circuit SP and a normally-off n-channel MOSFET MT for providing constant currents which can be generated independently of the load or independent of the operating voltage Vss present at the first current connection SA1 and are not influenced by the voltage fluctuations of the operating voltage Vss. The current mirror circuit in turn comprises an SP Refe rence ^¬ current path RD and a load current path LD, said two current paths RD, LD to each other substantially mirror-symmetrical. The reference current path RD comprises a bipolar transistor BT1 and a resistor R21 connected in series. Analogously, the load current path LD comprises a further bipolar transistor BT2 and a further resistor R22, which are connected in series. In this case, the two bipolar transistors BTL, BT2 of the same design and the same dimensions. The two resistors R21, R22 are dimensioned according to the current amplification factor of the current mirror circuit SP.

The base terminals of the two bipolar transistors BT1, BT2 are connected to one another and to the collector terminal of the reference current path-side bipolar transistor BT1 and via a further resistor R23 to the second one mentioned above Power connection SA2 of the circuit device SV electrically connected.

Via the second current connection SA2, the current mirror circuit SP is supplied with a constant DC voltage which is far below 60 volts.

The load current path LD positive voltage side connected to the negative terminal NA electrically.

On the negative voltage side of the load current path LD and the Re ^¬ ferenzstrompfad RD are electrically connected to each other and to the ground terminal ML and thus to the electrical ground MS. The reference current path RD is electrically connected to a positive voltage side or on the collector terminal to the drain terminal of the above-ge ^¬ called n-channel MOSFET MT.

The n-channel MOSFET is thus MT via the drain terminal connected to the collector terminal of the reference current path side Bipolart ^¬ ransistors BT1 and to the base terminals of two bipolar transistors BT1, BT2 are electrically connected.

The MOSFET MT is electrically connected via the source terminal to the ground terminal ML and thus to the electrical ground MS.

Via the gate terminal, the MOSFET MT is electrically connected to a signal terminal SS via which a control signal for switching the MOSFET MT is applied to the gate terminal. Further, the gate terminal is electrically connected to the ground terminal ML via a pull-down resistor R24.

The circuit device SV also comprises a measuring arrangement MA, which is also electrically connected between the negative terminal NA and the ground terminal ML.

The measuring arrangement MA comprises a measuring path MD, which is located between the negative terminal NA of the circuit device SV and the Ground terminal ML extends and includes a first resistor R31, a second resistor R32 and a capacitor C, which are connected in series between the negative terminal NA and the ground terminal ML. The two resistors R31, R32 serve to stabilize the voltage potentials Φ, which are measured by the measuring arrangement MA in a manner to be described below. The capacitor C compensates the voltage fluctuations in the measuring path MD. The measuring arrangement MA comprises a protective circuit unit SE, which in turn comprises two diodes Dl, D2, which are connected between the aforementioned third power connection SA3 of the circuit ^¬ device SV and the ground terminal ML in series and in their respective forward direction of the third power connection SA3.

The protection circuit unit SE is electrically connected to a connection point API of the measurement path MP via a center tap MB, which electrically connects the two diodes D1, D2 to one another, which electrically connects the two resistors R31, R32 to one another.

The protection circuit unit SE is set up to limit the signal value of the measurement signal measured at the negative terminal NA between a voltage potential applied to the third current connection SA3 and the ground potential and thus to protect a detection arrangement EA to be described below from overloading by overvoltages. The circuit device SV also comprises the aforementioned detection arrangement EA, which is signal-connected via a signal input SG to a connection point AP2 of the measurement path MP with the measurement arrangement MA, wherein the connection point AP2, the second resistor R32 and the capacitor C of Messan- order MA with each other electrically connects and at the same time forms a signal output of the measuring arrangement MA. The determination arrangement EA comprises a comparator KP (that is to say a comparison unit) which compares the measured values relayed by the measurement arrangement MA directly with predetermined reference values. Alternatively or additionally, the determining arrangement EA comprises an analog-to-digital converter which is adapted to the measured by the measuring device MA and the determining arrangement EA transmitted analog measurement values to digital values to convert, which then determines from the Determined ^¬ lung arrangement EA in advance and as a digital Quantities stored reference values are compared.

The operation of the shock protection circuit BS previously described with reference to Figure 2 and in connection with different states in the to be monitored Hochvoltkom- components HK and in the locking loop conductor VS will be ^¬ written.

The contact protection circuit BS monitors the states of the housing and the other insulation measures of the high-voltage components HK by means of the locking conductor loop VS, in particular by means of the switch or switches ST in the locking conductor loop VS. In particular, the following states are determined or recognized:

Condition 1: As long as the housings of the high-voltage components HK are closed without errors and the insulation measures of the

High-voltage components HK work properly, and thus the high-voltage components HK are electrically isolated from the environment safely, the switch ST in the locking ^¬ conductor loop VS in a manner known to those skilled

(compare the document WO 2009/112165) closed ge ^¬ hold. In these error-free states, the first and second line ends LEI, LE2 of the interlock conductor loop VS are electrically short-circuited to one another via the closed switches ST.

Condition 2: As soon as one or more housings or one or more insulation measures of the high-voltage components HK are damaged or unintentionally caused by, for example, a mechanical action opened or deactivated, so one or more switches ST in a manner known to those skilled open (see the document WO 2009/112165). Consequently, the interlock conductor VS is broken and the two line ends LEI, LE2 of the interlock conductor VS are electrically disconnected from each other.

State 3: A faulty connection or other fault can electrically short-circuit the interlock conductor loop VS, which is normally closed (i.e., not electrically isolated), at the first power port SA1 and thus at the external power source.

State 4: Analogously, the interlock conductor loop VS, which is closed by itself (and thus is not electrically isolated), be electrically shorted by a faulty connection or other errors on the ground terminal ML and thus on the electrical ground MS. Other states: There are also other states of the Verrie ^¬ gelungsleiterschleife VS, which can not be clearly assigned to any specific failure of the locking conductor loop VS. However, these states clearly differ from the aforementioned states 1 to 4.

The aforementioned states of the locking conductor loop VS are recognized by the circuit device SV in the manner to be described below. In order to check which of the above states exists, the gate terminal of the MOSFET MT of the current source is connected in a first measuring process according to a method step S100 via the signal terminal SS SQ applied a first control signal with a Sig ^¬ nalpegel logic "low" (typically with a signal voltage of 0 volts). As a result, the MOSFET MT is opened and the reference current path side bipolar transistor BT1 is closed. Thereby, the power source SQ becomes active and generates a constant DC current II through the Load current path LD and thus from the first power terminal SAl via the load current path LD to the ground terminal ML flows.

If the above-mentioned condition 1 is present (the housings and other insulation measures of the high-voltage component HK are faultless) and thus all the switches ST in the locking conductor loop VS are closed, the direct current II generated by the current source SQ flows divided by the current-limiting circuit SB and partly through the latter Resistors R12, R13 of the current limiting circuit SB to the interlock conductor VS and partly directly to the bridging resistor Rb.

The operating voltage Vss applied to the first current connection SA1 then drops across the resistors RH, R12, R13 and the bridging resistor Rb and the resistor R22. A voltage potential Φ (or the voltage between the negative terminal NA and the ground terminal ML), whose value is smaller than the value of the operating voltage Vss but is close to this value (due to the triple parallel connection of the three resistors R12, R13 and Rb due to the closed Verriegelungslei ^¬ terschleife VS).

If the above-mentioned state 2 is present (one of the housings opened or one of the other insulation measures is faulty) and thus the corresponding switches ST are open and consequently the interlocking conductor circuit VS is also interrupted, the direct current II generated by the current source SQ flows from the first power connection SAl exclusively via the bypass resistor Rb to the ground connection ML.

Due to the interruption of the locking conductor loop VS, no current flows through the parallel current path SD2 via the two resistors R12, R13. As a result, the total electrical resistance between the first power connection SA1 and the negative connection NA will be somewhat greater than the total resistance of the triple parallel connection in the state 1. Consequently, a voltage potential can be applied to the negative connection NA. whose value is below the value of the operating voltage Vss and also below the value of the voltage potential Φ measured at the state 1. If the above-mentioned condition 3 from (the Verriegelungslei ^¬ terschleife VS at the electrical connection SA1 electrically shorted ^¬ closed), and thus the negative terminal NA is electrically shorted to the power terminal SA1, a voltage potential Φ is measured to the negative terminal NA, the value of the value of the operating voltage Vss is close.

If the above-mentioned state 4 at the moment (the Verriegelungslei ^¬ terschleife VS to the ground terminal ML electrically shorted ^¬ closed), and thus the negative terminal NA is electrically shorted to the ground terminal ML, a voltage potential Φ is measured to the negative terminal NA, the value of close to the value of the ground potential.

The voltage potential at the negative terminal Φ NA is measured according to a further process step S200 of the measuring arrangement MA and passed as a first potential measured value of Φ1 Determined ^¬ lung arrangement EA.

The first potential measured value Φ1 is then compared by the determination arrangement EA according to a further method step S300 with a first and a second predetermined potential reference value Url, Ur2, where: Url <Ur2.

Furthermore, in a second measuring operation according to a further method step S400, a second control signal with a signal level of "logic one" (usually with a voltage of 5 volts) is applied via the signal terminal SS to the gate terminal of the MOSFET MT MOSFET MT is closed and the two bipolar transistors BT1, BT2 are opened, causing the current source SQ to become inactive Consequently, no current or current 12 having a current of 0 amperes will flow to the first current terminal SA1 via the load current path LD to the ground terminal ML. If one of the states 1, 2 or 3 is present, then a voltage potential Φ is measured at the negative terminal NA whose value (as a second potential value Φ2) is close to the value of the operating voltage Vss.

If the above-mentioned state 4 is present, a voltage potential whose value is close to the value of the ground potential is measured at the negative terminal NA. The voltage potential Φ at the negative terminal NA is measured by the measuring arrangement MA according to a further method step S500 and forwarded as a second potential measured value Φ2 to the determining arrangement EA. The second potential reading Φ2 then from the

Detection arrangement EA according to a further method step S600 compared with a third and a fourth predetermined potential reference value Ur3, Ur4, where: Ur3 <Ur4. If the first potential measurement value Φ1 between the first and the second potential reference value url and Ur2 and at the same time the second potential measurement value Φ2 is greater than the fourth potential ^¬ reference value UR4 (ie, when a following logic operation is satisfied: Url "I> l <Ur2 &UR4"I> 2), it is recognized that the state 1 is present and the locking conductor loop VS is closed without errors.

Is the first potential measurement value Φ1 smaller than the first Po ^¬ tentialreferenzwert gap and at the same time the second potential measurement value Φ2 is greater than the fourth potential reference value UR4 (ie, when a following logical operation is true: <I> l <Url & UR4 "I> 2 ), it is recognized that the condition 2 is present, and one of the switches ST is open and thus the Verriegelungslei ^¬ terschleife VS is electrically interrupted.

Is the first potential measurement value Φ1 greater than the second Po ^¬ tentialreferenzwert Ur2 and at the same time the second Potenti ^¬ almesswert Φ2 is greater than the fourth potential reference value UR4 (Thus, a following logical link is satisfied: Ur2 <1 & Ur4 <cj> 2), it is recognized that the state 3 is present and the locking conductor loop VS is electrically shorted to the first power terminal SAl or the voltage source.

Is the first potential measurement value Φ1 smaller than the first Po ^¬ tentialreferenzwert gap and at the same time the second Potenti ^¬ almesswert is Φ2 smaller than the third potential reference value Ur3 (ie, when a following logic operation is satisfied: KURL & 2 <Ur3), so it is detected that the state 4 is present and the locking conductor loop VS is electrically short-circuited to the ground terminal ML or the electrical ground MS.

If there is a logical link deviating from the above-described links between the two potential measured values Φ1, Φ2 and the four potential reference values Url, Ur2, Ur3 and ur4, then it is recognized that one of the aforementioned further states that can not be unambiguously assigned exists. If the faulty condition 2 is detected, the Determined ^¬ lung arrangement EA is by supplying a signal to a not-shown in the figure, the central control device of the electric vehicle, and causes them the high-voltage components HK, for example, by discharging or by electrically separating from the electrical system of the To disable electric vehicle.

If the faulty state 3 or 4 is detected, the determining arrangement EA gives, for example, by emitting a further signal to a vehicle signal display device (not shown in the figure) and makes the driver of the vehicle

Electric vehicle to the faulty condition attentive so that this brings the electric vehicle to repair the contact protection circuit BS in a vehicle workshop.

Claims

Circuit means (SV) for detecting a state of an electrical interlock conductor loop (VS) for monitoring at least one high-voltage component (HK) to collectively ^¬:

a power terminal (SA1) for electrically connecting to a power source;

a ground terminal (ML) for electrical connection to an electrical ground (MS);

a positive terminal (PA) for electrical connection to a line end (LEI) of the Verriege ^¬ ment ladder loop (VS);

a negative terminal (NA) for electrical connection to another line end (LE2) of the interlock conductor loop (VS);

a measuring arrangement (MA) for measuring the voltage potential (Φ) at the negative terminal (NA) at two different currents (II, 12) flowing from the current terminal (SA1) via the negative terminal (NA) to the ground terminal (ML) ;

a determining arrangement (EA) comprising a comparison unit (CP) for comparing the two when the two streams (II, 12) measured potential values (Φ1, Φ2) of the voltage potential (Φ) (each having two pre ^¬ given potential reference values Url, Ur2 and Ur3, Ur4) and is set up, based on the Ver ^¬ equal results of the comparison unit (KP) to detect whether the negative terminal (NA) to the positive terminal (PA), the power connector (SA1) or the ground terminal (ML), or is electrically shorted to any of these terminals (PA, SA1, ML).

A circuit device (SV) according to claim 1, further comprising a controllable current source (SQ) for providing the two currents (II, 12) electrically connected between the negative terminal (NA) and the ground terminal (ML). Circuit device (SV) according to claim 2, wherein the current source (SQ) is designed as a constant current source or as a scalable or modulatable current source.

A circuit device (SV) according to claim 2 or 3, wherein the current source (SQ) comprises a current mirror circuit (SP).

Contact protection circuit (BS) for monitoring at least one high-voltage component (HK), comprising:

an electrical interlock conductor loop (VS) for monitoring the at least one high-voltage component (HK);

a circuit device (SV) according to one of the preceding claims for determining the state of the interlock conductor loop (VS),

wherein the switching device (SV) through the positive terminal (PA) with one line end (LEI) of the Ver ^¬ lock-out the conductor loop (VS) and the negative terminal (NA) with a further pipe end (LE2) is electrically connected to the lock conductor loop (VS).

Vehicle, especially hybrid electric or electric vehicle to ^¬ collectively.:

at least one high-voltage component (HK),

at least one contact protection circuit (BS) according to claim 5 for monitoring the at least one high-voltage component (HK).

Method for determining a state of an electrical interlock conductor loop (VS) for monitoring at least one high-voltage component (HK) with a circuit device (SV) according to one of Claims 1 to 4, comprising the following steps:

Generating (S100) a first current (II) flowing from the power terminal (SA1) via the negative terminal (NA) to the ground terminal (ML); Measuring (S200) the voltage potential (Φ) to the ne ^¬ gativen connection (NA), while the first current (II) flows;

Comparing (S300) a first measured potential measurement value (Φ1) with a first (Url) and a second (Ur2) potential reference value, where

Url <Ur 2;

Generating (S400) a second current (12) flowing from the power terminal (SA1) via the negative terminal (NA) to the ground terminal (ML);

Measuring (S500) the voltage potential (Φ) to the ne ^¬ gativen connection (NA), while the second stream (12) flows;

Comparing (S600) the measured second potential measurement value (Φ2) with a third (Ur3) and a fourth (Ur4) potential reference value, where Ur3 <Ur4;

wherein an error-free state of the Verriegelungslei ^¬ terschleife (VS) is detected if the first Po ^¬ tentialmesswert (Φ1) between the first (Url) and the second (Ur2) potential reference value and the second potential measurement (Φ2) is greater than the fourth Poten ^¬ tial reference value (Ur4).

The method of claim 7, wherein electrical disconnection of the locking conductor loop (VS) is detected, if the first potential measured value (Φ1) is smaller than the first potential reference value (URL) and the second Potenti ^¬ almesswert (Φ2) is greater than the fourth potential reference value (UR 4) is.

The method of claim 7 or 8, wherein an electric short-circuit of the latch conductor loop (VS) to the power supply (SA1) is detected if the first Po ^¬ tentialmesswert (Φ1) is greater than the second Potentialre ^¬ reference value (Ur2) and the second potential measurement value ( Φ2) is greater than the fourth potential reference value (Ur4). Method according to one of claims 7 to 9, wherein an electrical short circuit of the locking conductor loop (VS) to the ground terminal (ML) is detected if the first potential measurement value (Φ1) is smaller than the first potential reference ^{value ¬} (Url) and the second potential ^{measurement value} ( Φ2) is smaller than the third potential reference value (Ur3).